This research is a laboratory study to improve the geotechnical properties of fine-grained soils. For this purpose, agricultural waste ash such as sugarcane bagasse, rice husk and almond husk have been used. In this regard, the effect of using ash of the mentioned fibers with at 4, 8 and 12 weight percentages on fine grain clay soils has been investigated. The compaction test results indicate that these additives generally increase the optimum soil moisture and the maximum optimum moisture was observed for the samples made with 12% ash. Also, based on the results of the unconfined compressive strength test, the studied additives have increased the uniaxial strength of the soil. The samples made with 12% ash were the most effective, so that the addition of 12% bagasse ash increased the soil resistance by 117%, and the addition of 12% rice husk ash and almond husk ash increased the soil resistance by 89, 80% respectively.
